This application relates generally to laminated cores for electric machines. More particularly, this application relates to cores formed from a plurality of stacked segments and the methods and apparatus used in the manufacture of such laminated cores.
Electric machines include stators and rotors that employ a plurality of stacked layers of electrical steel.
By way of example, an electric machine 10 is provided in FIGS. 1 through 3. Electric machine 10 includes a stator core 12 and a rotor core 14. Cores 12 and 14 are formed of a stack of layers 16. Layers 16 are formed of electrical steel, namely steel having high silicone content. Each layer 16 is coated with an insulating coating 18. An example layer 16 of stator core 12 is illustrated in FIG. 3. Here, layer 16 includes a central bore 20 for receiving rotor core 14 and a plurality of spaced apart notches 22 for receiving motor windings 23.
Several prior methods have been used to manufacture layer 16 and/or cores 12 and 14. For instance, a complete layer 16 has been stamped from a blank sheet of stock. However, this single stamping system provides poor material utilization of the stock material, which leads to higher manufacturing costs.
In another method, cores 12 and 14 have been manufactured using a continuous stamped layer of insulated electrical steel 24 as illustrated in FIG. 4. Continuous stamped layer 24 is wound about an arbor 26 to form cores 12 and 14. Arbor 26 includes blades 28 that receive and align notches 22 of the layer to the arbor. A feed gear (not shown) feeds continuous stamped layer 24 into forming rollers 27. Arbor 26 is geared/timed to the feed gear. Forming rollers 27 are adapted to form a radius corresponding to the radius of arbor 26 in continuous stamped layer 24. Thus, rotation of arbor 26 draws continuous stamped layer 24 (having its notches 22 aligned by blades 28) about the arbor to form cores 12 and 14 as a helically wound core. This helical winding method provides superior material utilization as compared to the single stamping method described above. However, such helical winding methods require large initial investment in the equipment necessary to wind continuous stamped layer 24 about arbor 26.
A segmented core for an electric machine is provided. The segment core includes segments stamped from coated electric steel. The segments each have a first end, a second end, and winding openings. A predetermined number of segments are placed end-to-end to form layers. The layers are stacked such that each of the layers is staggered from adjacent layers by a predetermined rotation angle. The winding openings of each of the layers are in vertical alignment with the winding openings of the adjacent layers. The stack of layers is secured to form the segmented core.
An apparatus for manufacturing a segmented core for an electric machine is provided. The apparatus includes a stacking head, a dial and a support table. The stacking head has a magazine, a stripper blade and a stripper blade actuator. The magazine is sized, dimensioned and positioned to receive segments stacked one on top of the other. The segments are stamped from coated electric steel. Each segment has an annular length and winding openings. The dial has an arbor and means for rotating the dial. The arbor has an outer diameter approximately equal to an inner diameter of the segmented core. The arbor also has radially extending blades being sized, positioned and dimensioned to engage the winding openings. The support table supports the stacking head and the dial. The support table also includes rollers disposed about the arbor at an outer diameter of the segmented core. A controller controls the stripper blade actuator and the rotating means. The controller forms layers from the segments by rotating the dial the first predetermined angular distance, extending the stripper blade, and retracting the stripper blade until one of the layers is complete. The controller staggers the layers by rotating the dial the second predetermined angular distance between each completed layer.
A method of making a segmented core for an electric machine is provided. The method includes stamping lamination segments, forming layers from the lamination segments, stacking the layers in a staggered fashion, and securing the stack of layers to form the segmented core. The lamination segments are stamped from a blank of coated electrical steel. Each lamination segment has a first end, a second end, and winding openings. The layers are formed placing a predetermined number of lamination segments end-to-end such that the first end of one of the lamination segments is adjacent the second end of another of the lamination segments. The layers are staggered by rotating adjacent layers by a predetermined rotation angle such that the winding openings of each of the layers are in vertical alignment with the winding openings of the adjacent layers.
The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.